The Society for Pediatric Anesthesia (SPA) has released a set of recommendations to reduce the incidence of transfusion-associated hyperkalemia and associated cardiovascular risks, such as cardiac arrest. These recommendations, issued on August 16, 2011, by SPA and its Patient Safety Organization, Wake Up Safe, may stimulate changes in requests for red blood cells by pediatric anesthesiologists.

SPA issued their recommendations to the pediatric anesthesiology community after reviewing four recent cases reported to Wake Up Safe. These cases describe significant cardiovascular changes intraoperatively, associated with the transfusion of large volumes of irradiated RBCs. A number of transfusion-associated hyperkalemia case reports over the years (11 case reports since the 1970's, and eight additional cases reported to a pediatric registry 1998-2004) raised related concerns. The previous 19 case reports describe infants with a variety of diagnoses and were not limited to patients with underlying cardiac disease.

In brief, specific recommendations from SPA that may impact Transfusion Services include the following:

The use of fresh red blood cells products (less than 7 days from collection) in cases where massive transfusion is anticipated.

If irradiation of the product is indicated, transfuse it as soon as possible after irradiation.

If red blood cells with relatively high potassium levels are the only readily available option, the unit can be washed prior to transfusion. Note that the recommendations from SPA included the use of perioperative salvage devices (such as a Cell Saver ®) as an institution-dependent alternative.

AABB shares the Society for Pediatric Anesthesia's concerns about the risk of transfusion-associated hyperkalemia and agrees that steps should be taken to reduce the incidence of this life-threatening condition. However, the recommendations made by SPA lack clarity regarding some issues, do not emphasize some possible approaches to minimize the risk of hyperkalemia, and include some detailed recommendations based on limited, inconclusive evidence.

In response to inquiries based on the SPA recommendations, the following issues should be considered in discussions with your institutions' pediatric anesthesiologists:

The pediatric population that is at-risk is not precisely defined. Based on the reports, it most likely would only be applicable to infants one year and younger.

The safe concentration of extracellular potassium in transfused units has not been determined, nor was the definition of a large-volume transfusion presented in the recommendations. There is general agreement within the transfusion medicine community that a large-volume transfusion is usually considered to be greater than 20-25 ml/kg patient weight. The volume required for ECMO or CV by-pass circuit prime can also represent a "massive transfusion" for smaller patients (especially those under five kilograms).

The time period between irradiation and transfusion that results in adverse events is not defined. In the four cases that were reviewed, irradiation was performed on the day of use. There are no good published data on how quickly potassium levels rise in the hours immediately following irradiation.

The rate of the increase of potassium levels during the early period of storage, prior to irradiation, is also unknown. Whether the use of RBCs less than 7 days vs. less than 10 days or some other time is an appropriate cutoff for the definition of "fresh" blood is unknown.

Washing red blood cells requires time and resources that are not always available in every hospital, and may not be necessary if other precautions are taken with regards to minimizing the risk of hyperkalemia. Furthermore, washing requires time that may not be consonant with rapid blood needs in massive transfusion situations. Additionally, washing can induce hemolysis and the extracellular potassium concentration rises more rapidly following washing than during regular storage.

Perioperative salvage technology (e.g., Cell Saver ®) has not been FDA-approved to wash allogeneic blood; these devices have been designed and approved to salvage blood shed in the surgical field. Also, intraoperative blood salvaged expires four hours after completion of processing, resulting in limited shelf-life.

Additional approaches to minimize the risk of hyperkalemia can include:

Management of the patient's pre-transfusion potassium levels.

Transfusion through a peripheral infusion line.

Active monitoring of potassium levels during transfusion.

The use of additive units, since they have lower concentrations of extracellular potassium than CPDA-1 units of a similar age; note, however, that the safety of large transfusions of additives to neonates has not been studied in clinical trials.

Additive (supernatant) removal.

AABB is actively engaging experts in Pediatric Transfusion Medicine to examine this issue further to help bring some clarity to issues described above. AABB will continue our ongoing efforts to work with the Society for Pediatric Anesthesia to improve patient care for pediatric transfusion recipients across the U.S. The association will offer further guidance to members as additional data become available. If you have questions or comments regarding this issue, please contact govt&legal@aabb.org.